We're setting up Appointments+ here, and we have the "require user to be logged in" setting checked, but when we try to click an open appointment time with any user account while logged in (any user role), we get a "You need to be logged in" popup alert.
I tested the plugins' login check by using the [app_schedule logged="Logged in!" notlogged="Not Logged in!"] shortcode, and the system echoes the correct string based on a user's login status.
I should mention we're also using Membership 2, and this page is locked to our one and only membership level. I've tried my appointment test with the page's Membership Access control enabled and disabled, with no change. I've also tried with Membership 2 disabled entirely.
I see no JS errors on my browser console, and no errors in my PHP logs, either.
Have enabled support access for you guys.